Thanks to all who have contributed to this thread for helping me get up and running with inadyn and freedns.afraid.org. A couple of things I noticed as I read through this thread that tripped me up:

-Scheduling inadyn to start at reboot using cron is a good idea, however scheduling it to run every 5 minutes as previously suggested might be a bad idea. The reason for this is that every 5 minutes, cron starts a new instance of inadyn while the old instance is still running.. so after an hour, you'd have 12 instances, after a day, 288 instances, etc.

-I couldn't get forced update checking to work - inadyn was updating the IP when cron started it right after a reboot, but it wasn't updating every 5 minutes as it was supposed to after that, even though the daemon was still running. I was starting to think I was going to have to kill the daemon after every update and then have cron run it every 5 minutes as previously discussed... until I realized that the --forced_update_period argument is in SECONDS, not MS. Updating the inadyn.conf file to show:

--forced_update_period 300

fixed the problem for me and allowed inadyn to update my IP every 5 minutes as intended. It is a bit confusing that update_period uses MS and forced_update_period uses SECONDS.

The OP's post shows a forced_update_period of 320000. This results in a forced update every 88 hours. Not sure if this was intended or not, but if you are wanting to force an update more frequently like I did, make sure you are calculating this value in SECONDS.